Electrochemical Reconstruction of Metal Surfaces

ABSTRACT

The invention relates to methods and compositions for the surface reconstruction of gold and other metal surfaces. Specifically, an applied potential and a certain solution composition, is used to reconstruct the metal surface atoms into a specific atomic lattice arrangement (symmetry). Also disclosed is a kit for the surface reconstruction of metal electrodes.

RELATED APPLICATIONS

This substitute application contains no new matter and relates to U.S.Non-Provisional patent application Ser. No. 12/329,630, which was filedDec. 7, 2008. This application relates to and claims priority to U.S.Provisional Patent Application No. 61/007,266, which was filed Dec. 12,2007 and is incorporated herein by reference in its entirety.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The invention was made with government support under U.S. Army contractDAAD19-2-D-0001-0574. The government may have certain rights to theinvention.

FIELD OF THE INVENTION

The present invention relates to methods and compositions for thereconstruction of metal surface atoms into a specific atomic latticearrangement (symmetry) using an electrochemical technique. Specifically,the invention combines a potential sweep method and a specific solutioncomposition to yield a specific metal surface lattice arrangement(symmetry) over the entire surface area within a few minutes.

BACKGROUND OF THE INVENTION

The type of metal, its crystal structure and defects, cleanliness andsurface pretreatments can play an important role in self assembly andprotein/enzyme electron transfer.^(3, 4, 8-11) Therefore establishing areproducible electrode surface for the self assembly of monolayers,bilayers and enzymes or proteins was considered using electrochemicalsurface reconstruction. A rearrangement of surface atoms as a functionof potential and solution composition, which often involves a change inthe surface atoms symmetry (or atomic lattice arrangement) androughness, is called electrochemical surface reconstruction. Surfacereconstruction phenomena have been extensively studied since its proofof existence in the early 80's and literature reviews on surfacereconstruction are available.^(12, 13)

Electrochemists are interested in gold because of its inertness(resistance to oxidation) and the wide polarizable potential rangesaccessible in ultra high vacuum and aqueous media.¹ A few importantapplications of gold include jewelry, semiconductor technology, fuelcells, and as substrates for self assembling monolayers and bilayers.Gold substrates are also used as electrode platforms for immobilizingfully functional enzymes in lipid bilayers or immobilizing proteins ontop of self assembled monolayers.²⁻⁴ Because of these applications andproperties of gold metal, it was initially examined by this invention.Commercially available gold electrode substrates include bulkpolycrystalline, evaporated, single crystal gold and gold grown on mica.In this work evaporated gold on quartz was selected for the workingelectrode because of the piezoelectric properties of properly cut andmounted quartz.

The piezoelectric properties enable gold quartz crystals electrodes toserve as mass sensitive weighing platforms in quartz crystalmicrobalances (QCMs).⁵⁻⁷ The QCM can resolve very small adsorption anddesorption mass changes from electrode surfaces with a mass-measuringsensitivity of 0.1 nanograms. This technique uses the changes inresonance frequency of the crystal to measure the mass on the surfacebecause the resonance frequency is highly dependent on any changes ofthe crystal mass. Another attractive quality is that QCM electrodes arerelatively inexpensive when compared to single crystals (˜$16 versus$300) and mechanically stronger, but as with every electrode or type ofmetal, there are pros and cons. One problem with QCM electrodes is thatgold does not adhere very well to surfaces like quartz or glass. Thisadhesion problem is usually overcome by depositing a thin metalundercoating such as titanium or chromium. However, based on the dataobtained in this lab and earlier publish data, using a chromium adhesionlayer can be problematic especially in the gold oxide potential regionand so a titanium adhesion layer was used.⁸

SUMMARY OF THE INVENTION

The invention provides simple and effective methods and compositions forthe reconstruction of gold surfaces into the specific surface latticearrangements of (111) and (110). Those of skill in the art ofelectrochemistry will recognize that additional lattice arrangementscould be tailored using different solution compositions and that othermetals could also be tailored to specific lattice arrangements using thesame or different potentials and solution compositions.

The invention provides a simple and effective methods and compositionsto quickly change the metal lattice surface arrangement within a fewminutes over a large area. The invention does not require large orexpensive equipment to perform or interpret the results. Ultra highvacuum conditions are not required in order to perform the surfacereconstructions. The reconstructions are stable in air and the metalsurface can be mailed via the postal system.

The invention provides reconstruction of the metal into a specificlattice arrangement and is independent of the metal's surface area andcould be applied quickly to very large sheets of metal or tonanoparticles.

The invention provides a simple and effective method for thereconstruction of the gold surface into a (111) lattice arrangementwithout using flame annealing.

The invention also provides for kits to reconstruct metal surfaces.These kits comprise of different chemical solutions, electrochemicalcells, reference and auxiliary electrodes.

Other objects, features, and advantages of the present invention willbecome apparent from the following detailed description. It should beunderstood, however, that the detailed description and the specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows voltammogram comparisons of the evaporated gold surface asreceived, after potential cycling in acidic chloride solution and afterpotential cycling in 0.1 M PB, pH 7.4 with ATCA. The peak voltage,charge from the gold oxide cathodic stripping peak and roughnessmeasurements are tabulated. Results from the as received electrode arein purple, after potential cycling in acidic chloride solution are inblue, and after potential cycling in 0.1M PB, pH 7.4 with ATCA are inred.

-   -   ^(a) Determined from electrochemical roughness scans using 448        μC/cm² as the theoretical value.¹⁴    -   ^(b) R_(f−E/C)* normalized to the flattest experimental gold        substrate (Au epitaxial growth on cleaved mica) in the following        manner:¹⁴        -   ▭ Qred-theor/Qred-exp (Au/mica)=448 μC/cm²/358 μC/cm²=1.25        -   Therefore, each Rf−E/C value was multiplied by 1.25 to            obtain an adjusted/normalized value.    -   ^(c) The root mean square (RMS) roughness known as R_(q) (nm)        determined from AFM scans (2.5 mm×2.5 mm)        -   Values listed for the AFM analysis are from QCEs that are            not depicted in FIG. 1.        -   However the AFM QCEs were treated the same as the QCEs in            FIG. 1 and had similar CVs.

FIG. 2 shows atomic force microscope analysis after solution 1 andsolution 2 surface reconstructions. Atomic Force Images were taken byDr. Mike Allen at Biometrology, Inc., 851 West Midway Avenue, Alameda,Calif. 94501 USA. (Website: www.biometrology.com) The atomic forcemicroscope (AFM) measurements were carried out using an extendedMultiMode AFM (MMAFM) integrated with the NanoScope IIIa controller(Veeco Instruments, Santa Barbara, Calif.). The MMAFM was equipped witha calibrated E-type piezoelectric scanner and suspended using a custombungee-type noise isolation system. The larger area scans were acquiredusing tapping mode while contact mode was used for atomic level AFM.Topographically flat subdomains were selected for atomic level scans.Results from the after potential cycling in 0.1M PB, pH 7.4 with ATCAare represented in sample 6 and after potential cycling in acidicchloride solution in sample 8.

FIG. 3 shows cyclic voltammograms in 1 mM Pb(NO₃)₂, 0.1 M KNO₃ and 0.1 MHNO₃ and the corresponding frequency changes for lead deposited on Au(111) and Au (110) surfaces. Results from the after potential cycling in0.1M PB, pH 7.4 with ATCA are represented in blue and after potentialcycling in acidic chloride solution in purple.

FIG. 4 shows cyclic voltammograms before and after both reconstructionsin 0.1 M KNO₃. Results from the as received electrode beforereconstruction are in light blue, after potential cycling in acidicchloride solution are in purple, and after potential cycling in 0.1M PB,pH 7.4 with ATCA are in dark blue.

FIG. 5 shows solution 1 reconstruction of the gold electrode surface.Cyclic voltammogram and the corresponding frequency changes.

FIG. 6 shows solution 2 reconstruction of the gold electrode surface andCV scans in 0.1 M phosphate buffer, pH 7.4 as compared to a scan withATCA in the 0.1 M phosphate buffer, pH 7.4. Results for CV scans in 0.1M phosphate buffer, pH 7.4 are in blue and purple and results for CVscan with ATCA added to 0.1 M phosphate buffer, pH 7.4 are in green.

FIG. 7 shows solution 2 reconstruction of the QCM electrode. Cyclicvoltammogram and the corresponding frequency changes.

DETAILED DESCRIPTION

The invention provides compositions and analytical procedures for theelectrochemical reconstruction of metal surfaces.

A. Reconstruction of Metal Surfaces

This invention uses a potential sweep method and a certain solutioncomposition to reconstruct the surface atoms of a metal into a specificatomic lattice arrangement (or symmetry). The reconstruction occurs inan electrochemical cell which is a non-reactive container (such asTeflon) which contains a certain solution and the working, auxiliary andreference electrodes. The metal to be reconstructed is used as theworking electrode and in this arrangement the potential of the workingelectrode is measured against the reference electrode while the currentis passed between the working and auxiliary electrodes. The workingelectrode potential is continuously varied and switching potentials areselected as to ensure metal oxide formation and reduction in a certainsolution. Depending on the solution composition, etching andredepositing, or etching and rearrangement, of the metal will also occurwithin the switching potential limits. The rate at which the potentialis varied is a constant value. The scan rate value is selected as toensure all reconstruction reactions are completed during the potentialsweeps and that the total reconstruction time is small.

The metal first examined by this invention was gold. Other metals ofinterest include, but are not limited to, platinum, silver, and copperand combinations thereof. Some of these other metals may requiredifferent solution compositions, different reference and auxiliaryelectrodes, and different switching potentials in order to create thesame atomic surface arrangements that were created with gold. Forexample the general chemistry rules of solubility will hinder using thesame solutions for some metals and the potential at which oxideformation occurs will be different for each metal.

B. Advantages Over the Art

The invention provides several advantages over the present art. Forexample, the reconstruction is fast, reversible and can be applied tolarge or small areas, including nanoparticles.

Only enough solution is needed to cover the metal area and to allow forcontact with the reference and auxiliary electrodes. This helps toeliminate hazardous waste.

The reconstruction process is fast which helps to eliminate work hoursand helps to lower power costs.

Equipment such as a scanning tunneling microscope (STM), atomic forcemicroscope (AFM), ultra high vacuum, and quartz crystal microbalance arenot required in order to perform the reconstructions.

C. Kits for Metal Surface Reconstruction

The invention provides for a variety of kit compositions. A kit may bedesigned to reconstruct one or more metal surfaces into one or moreatomic surface arrangements. Also a kit may be designed based on thesize of metal surfaces to be reconstructed and its future purpose.

DEFINITIONS

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of skill in theart to which this invention belongs at the time of filing.

The terms “reconstruction” or “electrochemical reconstruction” as usedherein refers to a rearrangement of surface atoms as a function ofpotential and solution composition, which often involves a change insurface symmetry and roughness.

The term “solution” as used herein refers to any aqueous or nonaqueoussolution used to reconstruct the metal surface.

The term “potential sweep method” as used herein refers to anelectrochemical method that continuously changes the potential of theworking electrode at a certain constant rate.

The term “switching potential” as used herein refers to the starting andend potentials in a potential sweep method.

The term “working electrode” as used herein refers to the metalelectrode at which the reconstruction takes place.

The term “solution 1” as used herein refers to a solution of 0.01M KCland 0.1M H₂SO₄.

The term “solution 2” as used herein refers to a solution of 0.1Mphosphate buffer, pH 7.4 with 10 mM 2-aminothiazoline-4 carboxylic acid(ATCA)

The term “container” as used herein refers to any vessel, tank, object,device, substance, material, particles, electronic, magnetic orgravitational fields, or space used to contain and create thereconstruction.

EXAMPLES

The following examples are included to demonstrate preferred embodimentsof the invention. It should be appreciated by those of skill in the artthat the techniques disclosed in the examples which follow representtechniques discovered by the inventor(s) to function well in thepractice of the invention, and thus can be considered to constitutepreferred modes for its practice. However, those of skill in the artshould, in light of the present disclosure, appreciate that many changescan be made in the specific embodiments which are disclosed and stillobtain a like or similar result without departing from the spirit andscope of the invention.

Materials and Methods:

A. Equipment

An electrochemical quartz crystal microbalance (QCM), model CHI430A—(CHInstruments, Austin, Tex.), was used to measure quartz frequency changesand electrochemical measurements. Solutions were prepared using ultrapure water that was purified using a Direct-Q3 system (MilliporeCorporation, Billerica, Mass.) to exhibit a resistivity of 18.2 MΩ cm.The solutions' pH were measured using a Corning model 440 pH meter(Woburn, Mass.). The Ag/AgCl, 1 M KCl reference electrodes were made inhouse and calibrated using a platinum wire immersed in a saturatedsolution of quinhydrone (Sigma-Aldrich, St. Louis, Mo.) of known pH.¹⁵Atomic Force Images were performed by Dr. Mike Allen at Biometrology,Inc., 851 West Midway Avenue, Alameda, Calif. 94501 USA. The atomicforce microscope (AFM) measurements were carried out using an extendedMultiMode AFM (MMAFM) integrated with the NanoScope IIIa controller(Veeco Instruments, Santa Barbara, Calif.). The MMAFM was equipped witha calibrated E-type piezoelectric scanner and suspended using a custombungee-type noise isolation system. The larger area scans were acquiredusing tapping mode while contact mode was used for atomic level AFM.Topographically flat subdomains were selected for atomic level scans.

B. Quartz Crystal Electrodes

Gold quartz crystal electrodes were obtained from International quartzcrystal manufactures (ICMFG). They consisted of 1000 Å gold onto 100 Åtitanium on an AT cut quartz crystal (10 MHz). The QCM electrodesgeometric area is 0.2 cm². A programmable JITO-2 reference oscillator(Mouser electronics, Mansfield, Tex.) with a reference frequency of10.005 MHz replaced the 8.005 MHz crystal in CHI QCM. By using theSauerbrey equation the change in mass can be determined. The Sauerbreyequation is represented by

${\Delta \; F} = {\frac{{- 2}f_{o}^{2}\Delta \; m}{{A\left( {\upsilon_{q}\rho_{q}} \right)}^{\frac{1}{2}}}\mspace{14mu} {where}\mspace{14mu} \frac{2f_{o}^{2}}{{A\left( {\upsilon_{q}\rho_{q}} \right)}^{\frac{1}{2}}}}$

corresponds to the QCM sensitivity constant.

D. Chemicals

Sodium dihydrogen phosphate monohydrate (ACS reagent >99%), sodiumhydroxide pellets (99.99%), potassium chloride (99.99%), potassiumnitrate (>99.5%), nitric and sulfuric acid (ACS reagent), and sodiumcyanide (>97%) were obtained from Sigma Aldrich.2-aminothiazoline-4-carboxylic acid (ATCA) was purchased from ChemImpex.

E. Electrochemical Cell

A Teflon container was used throughout these experiments. Allexperiments employed a double junction reference electrode (DJRE) andthe outer solution was replaced every two to three scans. The DJREconsisted of an outer chamber containing 0.1 M KNO₃ or 0.1 M phosphatebuffer, pH 7 and an inner chamber containing 1 M KCl and an AgCl coatedAg wire. A 0.5 mm diameter platinum wire served as the auxiliaryelectrode. All scan rates were 100 mV/s.

Example 1 Reconstruction of the Gold (110) Surface

The potential sweep method used switching potentials of −0.1 Volts and+1.5 Volts with −0.1 Volts selected as the initial starting potential. Ascan rate of 100 mV/s was selected and three complete cycles wereperformed. A solution of 0.01M KCl and 0.1M H₂SO₄ (solution 1) was usedto reconstruct the gold surface atoms into a gold (110) latticearrangement. The reactions of Cl⁻ at gold electrodes in acidic sulfatesolutions has been investigated earlier however this is the firstexamination of the atomic arrangement of the surface atoms.^(14, 16-18)In solution 1 the gold is first etched in the anodic scan and thenredeposited in the cathodic scan after gold oxide reduction.

Example 2 Reconstruction of the Gold (111) Surface

The potential sweep method used switching potentials of −0.1 Volts and+1.5 Volts with −0.1 Volts selected as the initial starting potential. Ascan rate of 100 mV/s was selected and three complete cycles wereperformed. A solution of 0.1M phosphate buffer, pH 7.4 with 10 mM2-aminothiazoline-4 carboxylic acid (ATCA) (solution 2) was used toreconstruct the gold surface atoms into a gold(111) lattice arrangement.The structure of ATCA is below:

Hoogvliet et al. showed an electropolishing effect of gold using 0.1 Mphosphate buffer, pH 7.4 and with a triple-potential pulse waveform.⁹The polishing process was suggested to be due to a reconstruction and adissolution of gold under flow conditions and the applied potentials.⁹However, in the presented invention, the experiments were performed inquiet (unstirred) solutions, the potential continuously changed, anorganic molecule was added to the phosphate buffer and this is the firstexamination of the atomic arrangement of the surface atoms. Thereappears to be no redepositing of gold and only slight dissolution (oretching) in solution 2. FIG. 6 illustrates the difference in the goldoxide potential region when ATCA is added to phosphate buffer. The morecharge and the anodic shift found in the gold oxide potential regionindicates that ATCA effects the gold oxide formation.

Examples 1 and 2 Reconstruction Confirmation Using Cyclic Voltammetry,Quartz Crystal Microbalance and Atomic Force Microscopy

Cyclic voltammetry was used to recognize the electrode surfacereconstruction and the results confirm the reconstruction of the surfacegold atoms into a (111) and (110) atomic arrangement. The first cyclicvoltammetry experiments were performed in a solution of 0.1M sulfuricacid. Cyclic voltammetry scans in dilute sulfuric acid can provide aqualitative assessment of the exposed crystal planes on the gold surfaceas well as the initial cleanliness.¹⁹ Multiple sharp peaks in the goldoxide potential region would suggest different crystal latticeorientations. A single sharp oxidation peak would indicate an Au(111)crystal orientated surface. FIG. 1 illustrates cyclic voltammograms(CVs) comparisons of the evaporated gold surface as received, afterpotential cycling in acidic chloride solution of 0.1M sulfuric and 0.01M KCl (solution 1), and after potential cycling in 0.1M phosphatebuffer, pH 7.4, with ATCA (solution 2). The initial scans usuallyrevealed a dominant Au (111) surface character in the evaporated goldQCE purchased from the supplier. After potential cycling in acidicchloride solution the surface atoms were altered to a different latticearrangement as suggested by the multiple peaks (Confirmed to be Au(110)by AFM). After potential cycling in solution 2 the surface was alteredback to Au(111) lattice arrangement as evident by the single sharpoxidation peak. It was also found that the initial surface needed to beclean and have a dominant Au(111) character in order for the Au(110)reconstruction CVs to be similar. For some QCEs, where the initial CVwas disordered in the gold oxide region, better results for the solution1 reconstruction could be obtained if solution 2 reconstruction wasperformed first.

The cyclic voltammogram can be used to estimate the surface roughness.Roughness is defined as the ratio of the real surface area to thegeometric surface area and can be approximated electrochemically bymeasuring the charge released in gold oxide reduction. ^(14, 20-22) Goldoxide (type I) reduction can be represented by the following reaction:²⁰Au₂O₃+6H⁺+3e⁻→+2Au+3H₂O. This electrochemical approach is a crudeapproximation to the surface roughness and is not well defined but hasfound some use for comparative purposes. The electrochemical roughnessfactor (R_(f−E/C)) is represented by the following equation:

$R_{f - {E/C}} = \frac{Q_{{red}{(\exp)}}}{Q_{{red}{({theor})}}}$

The crude approximation but usefulness of this approach can be explainedusing the tabulated data in FIG. 1. For example, the AFM analysis (whichis considered to be more accurate) for solution 2 reconstruction has thelowest R_(q) value. However the R_(f−E/C) for solution 2 reconstructionhas the largest value which is obviously contradictory to the AFMresults. In addition the peak potential has slightly shifted morenegative (˜13-19 mV) as compared to solution 1 reconstruction and the“as received” non-reconstructed electrode. The discrepancy in the chargevalues and the cathodic shift in the gold oxide reduction potentialmight suggest that additional chemistry is contributing to the charge.Perhaps gold oxide monolayers are more complete with the solution 2reconstruction even though the surface roughness is lower. It has beenshown that gold oxide reduction (and oxidation) is pH dependent, andthat a cathodic shift in the reduction potential and the oxide chargeincrease is due to a pH increase at the electrode surface.²⁰ Whenprotons are not consumed fast enough in the gold oxide reduction anaccumulation occurs at the surface increasing the pH. The reverse shouldbe observed for a decrease in pH. In these experiments type II or IIIoxide should not form because the switching potential is not largeenough and the oxides present are type I.²⁰ The QCM data (data notshown) for these scans indicated that sulfates were not adsorbed on thesurface after solution 2 reconstruction but were after solution 1reconstruction. It is possible that a completed and very stable type Ioxide monolayers were formed preventing sulfate adsorption but they weresupposedly reduced in the cathodic scan.²¹ It is speculated thatphosphates were absorbed after gold oxide reduction during thereconstruction and the sulfates were not able to displace them veryquickly.

The shape and peak potentials of the voltammogram contain informationabout the nature of the exposed gold crystal surfaces when lead isdeposited and removed.²³⁻²⁵ Lead strongly chemisorbs at the gold facesas a neutral adatom with Gibbs adsorption energies in the range 30 to100 kJ/mol.²⁴ In most lead deposition studies the perchlorate anion isused as the electrolyte because of its low tendency to specificallyabsorb on the gold/water interface.²⁶ However, perchlorate was notavailable for this research at USAMRICD and so nitrate anions were usedin the lead deposition. Earlier work has shown that the peak near −0.24V is associated with lead on the Au(111) surface, and the peaks near−0.24 V and near +0.02 V implies that lead is on a Au(110)surface.^(10, 24, 27) The Pb voltammetry is fairly reversible for theAu(100) and Au(110) faces but not for the Au(111) face.^(23-25, 28) Thepeaks are more clearly defined on the chemically etched electrodes andare quite broadened and ill-defined on polished electrodes. The “afterCl⁻ Recon” voltammogram in FIG. 2 shows both of these peaks which aremuch more reversible; just as expected for the Au(110) surface.

The frequency change measured with the QCM may be used to calculate themass of a deposited monolayer. Using the CHI software the QCM data inFIG. 2 was smoothed with the least squares method. A least squares pointof 7 and a FT cutoff of 30 (smoothed data not shown) was selected. Avalue of 59 Hz and 67 Hz was then read from the graph at 0.6 V. Using amass sensitivity parameter of 1.1 ng/Hz predicted by the Sauerbreyequation,^(6, 7) a 59 Hz frequency change corresponds to 3.25*10⁻⁷ g/cm²(or 1.57*10⁻⁹ mol/cm²) of lead deposited on Au(111) and a 67 Hz changecorresponds to 3.69*10⁻⁷ g/cm² (or 1.78*10⁻⁹ mol/cm²) of Pb deposited onAu(110). The diameter of lead is approx 3.501 Å whereas gold is approx2.884 Å.²⁹

Hz ng/Hz Pb g/cm² Pb mol/cm² Pb atoms/cm² Au(111) 59 1.1 3.25 * 10⁻⁷1.57 * 10⁻⁹ 9.43 * 10¹⁴ Au(110) 67 1.1 3.69 * 10⁻⁷ 1.78 * 10⁻⁹ 1.07 *10¹⁵Lead's nearest-neighbor distance was found to be 0.3459 nm in ahexagonal array of lead atoms.³⁰ The atomic coverage of Pb in ahexagonal close packed (hcp) monolayer of Pb is 9.4*10¹⁴ atoms/cm² (or1.6*10⁻⁹ mol/cm²).³¹ The same value was found for the Au (111) surfacein this work. The slightly larger value of atoms for the Au(110) surfacecould also be attributed to a hcp arrangement but with additional leadatoms acting to fill in the more open surface. FIG. 4 illustrates CVsperformed only in nitrate electrolyte (0.1M KNO₃) before and afterreconstruction of the QCEs. The “Before Recon” was initially performedon the gold QCE before any other experiments. After the solution 1 (Cl−)reconstruction a CV was again performed in nitrate electrolyte alone.The increase in double layer capacitance and its bent shape can beattributed to the increase in surface roughness and the more open andhighly stepped surface arrangement of the gold atoms. Then solution 2reconstruction was performed (after the solution 1 reconstruction) andthen a CV in 0.1M KNO₃ was again performed. Notice that the “Aftersolution 2 (ATCA) Recon” is very similar to the “Before Recon”. These CVscans in 0.1M KNO₃ for both reconstructions were reproducible. Thisreproducibility suggests that nitrate does not alter the reconstructionsand that the surfaces are stable in the potential region −0.4 to 0.6volts, which is suitable potential window for our work in proteinelectrochemistry.

The QCM data in FIG. 7 is very much different from the QCM data in FIG.5. In solution 1 the gold is first etched in the anodic scan and thenredeposited in the cathodic scan after gold oxide reduction. In solution2 (FIG. 6) there appears to be no redepositing of gold and only slightdissolution (or etching). The frequency shifts from the first cyclicscan is slightly different from the second and third cycles which arenearly identical. This would suggest that the surface reconstruction isalmost complete after the first cycle which also in agreement with thedilute sulfuric acid scans performed after the first and third cyclicscans. In the anodic scan some gold surface dissolution (or etching)from −0.2 V to ˜0.9 V is occurring due to the frequency increase and thefrequency decrease after 0.9 volts is likely due to gold oxideformation. In the cathodic scan, the gold dissolution appears tocontinue throughout the entire voltage window as evident by thecontinuing frequency increase after the gold oxide reduction whichstarts around 0.6 volts. It is suggested that gold dissolution and goldoxide formation is closer to equilibrium in the 2^(nd) and 3^(rd) scansand this accounts for the difference between the first cyclic scan andthe following cyclic scans. Future experiments are expected to confirmor suggest an alternate explanation for these differences.

The three low-index faces of gold, Au(111), Au(110) and Au(100) differin the density of atoms on their surfaces and in their symmetry. Themostly tightly packed is Au(111) which has three-fold (trigonal)symmetry with 1.39*10¹⁵ atoms per cm² and an atomic spacing of 0.29 Å.³²The more open Au(110), which is regarded as a highly stepped surface2(111)-(111), has two-fold symmetry with 1.70*10¹⁵ atoms per cm² and anatomic spacing of 0.32 nm.^(32, 33) Au(111) has an unit cell area of7.19 Å² and one atom in its unit cell. Au(110) has a unit cell area of11.79 Å² and two atoms in its unit cell. The atomic force microscope(AFM) can be used to obtain atomic resolution^(25, 34-38) and theelectrochemical surface reconstructions are readily apparent in theatomic force images of FIG. 2. Other analytical procedures that havebeen used to obtain evidence of atomic surface reconstruction can befound in Kolb's review.¹²

REFERENCES

The following references, to the extent that they provide exemplaryprocedural or other details supplementary to those set forth herein, arespecifically incorporated herein by reference. All patents andpublications referred to herein are incorporated by reference.

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1. Electrochemical methods for reconstructing gold metal surfaces into a specific lattice arrangement, with each method comprising: a container, potential sweep(s), switching potentials, electrodes and a specific solution composition.
 2. Electrochemical methods for reconstructing additional metal surfaces into a specific lattice arrangement, with each method comprising: a container, potential sweep(s), switching potentials, electrodes and a specific solution composition.
 3. The electrochemical methods of claim 1, wherein said methods do not require equipment such as a scanning tunneling microscope (STM), atomic force microscope (AFM) or quartz crystal microbalance to perform the reconstructions.
 4. The electrochemical methods of claim 1, wherein said methods do not require ultra high vacuum conditions in order to perform or preserve the reconstructions.
 5. The electrochemical methods of claim 1, wherein said methods create a stable reconstructed surface that can be mailed via the postal service without complicated precautions, storage and packaging.
 6. The electrochemical methods of claim 1, wherein said methods create a stable reconstructed surface that can also be stored in ultra clean conditions.
 7. The electrochemical methods of claim 1, wherein these methods include a method for obtaining the lowest energy atomic surface arrangement [Au(111)] without the use of flame annealing.
 8. The electrochemical methods of claim 1, wherein these methods are included in kits to reconstruct the gold surface. These kits comprise different chemical solutions, electrochemical cells, and electrodes (reference, auxiliary and working).
 9. The electrochemical methods of claim 2, wherein said methods do not require equipment such as a scanning tunneling microscope (STM), atomic force microscope (AFM) or quartz crystal microbalance to perform the reconstructions.
 10. The electrochemical methods of claim 2, wherein said methods do not require ultra high vacuum conditions in order to perform or preserve the reconstructions.
 11. The electrochemical methods of claim 2, wherein said methods create a stable reconstructed surface that can be mailed via the postal service without complicated precautions, storage and packaging.
 12. The electrochemical methods of claim 2, wherein said methods create a stable reconstructed surface that can also be stored in ultra clean conditions.
 13. The electrochemical methods of claim 2, wherein these methods include a method for obtaining the lowest energy atomic surface arrangement without the use of flame annealing.
 14. The electrochemical methods of claim 2, wherein these methods are included in kits to reconstruct the metal surface. These kits comprise different chemical solutions, containers, and electrodes (reference, auxiliary and working) for each metal. 